Cartridge case provided with a nonmetallic surface



April Z, 1940. J. KORPIUN 2,196,018

CARTRIDGE CASE PROVIDED WITH A NONMETALLIC .SURFACE Filed Aug.. 3, 1936INVENTQR Jaar/)fm Karp/0m,

Patented Apr. 2, 1940 UNiraD STATES PATENT OFFICE CARTRIDGE CASEPROVIDED WITH A NONMETALLIC SURFACE Application August 3, 1936, SerialNo. 94,055 In Germany August 3, 1935 7 Claims.

This invention refers to cartridge cases, and more especially tocartridge cases provided with a nonmetallic surface.

With cartridge cases for rifles, guns andthe like, made of brass,especially with those of larger calibers and when the barrels havebecome hot, the danger exists, that they are welded together with thegun barrel whereby in most of the cases the latter becomes completelyuseless. It should be possible to avoid or at least to substantiallydiminish said danger when using a raw material for making the cartridgecases the melting point of which is sufficiently high. Raw materialswith a melting point that is high enough for this purpose, however,cannot be employed in making cartridge cases on account of their highcosts and the fact that in general they can only be Workedwith-diiiiculty.

By the present invention a. new way to overcome said difficulties hasbeen found, that consists in providing suitable layers of separationbetween the cartridge case and the wall of the barrel, said layersexcluding metallic contact beg5 tween these two parts even when they arein a highly heated condition. Such layers of separation may consist, forinstance, of oxides or mixtures of oxides that have been produced uponthe cartridge itself by artificial means. Preferably the melting pointof the layer of separation 3 shan be higher than that of at least onemetal component of the alloy that might be formed on welding of thecartridge case and the wall of the barrel. The best results are achievedwhen the layer of separation is articiallyformed from S5 the basicmaterial of the cartridge caseitself.

The use of this inventive idea proved to be of special advantage whenemploying aluminum as raw material for the cartridge cases. A' uniformaluminum oxide layer of a high melting point as it is artificiallyproduced upon the aluminum by oxidation, is an especially suitable layerof separation for preventing the Welding together as well as theformation of an alloy between the highly heated metals; thereby thedanger of the 58 According to the electrolytic method the ox-V cartridgecase becoming welded together with.

idation' may be carried out, for instance, in a simple and convenientmanner in sulfuric acid or oxalic acid solution by means of alternatingor direct current. However, the use of baths of this type for carryingout the oxidation is not necessary; for, other electrolytic baths thatare suitable to produce oxide layers on aluminum by means of direct oralternating current may be employed likewise.

Besides the special property of preventing the m burning together ofcartridge case and barrel, such cartridge cases made of superficiallyoxl idized aluminum have the further' advantage that they possess a hardand smooth surface and hence, do not corrode even on storing the same ina moist atmosphere. Thus, such cartridge cases enable proper Working ofthe firearms under all conditions in contrast with cartridge cases ofbrass on the surface of which on storing in a moist atmosphere verdigrisand the like is formed, so causing their diameter to become enlargedover the admissible tolerance on account of the larger volume of theverdigris so that the charging of the firearm is impeded or otherdisturbances may take place. Furthermore itmight be mentioned that theuse of aluminum for cartridge cases means a considerable saving inweight.

Instead of the oxidic layer of separation on aluminum c-artridge casesthere may be used layers composed of other material, such as a fluorideor phosphate or the like layer.

Instead of valuminum also its alloys may be employed as raw material forthe cartridge case, whereby upon oxidation a mixture of the oxides ofthe metals in said alloys is produced.

Of course, many other changes and variations may be made by thoseskilled in the art in acf cordance with the principles set forth hereinand in the claimsannexed hereto. What I'claim is: 40

1. A cartridge case comprising an aluminum containing case adapted foruse in a gun barrel and an aluminum oxide layer thereon, said layerproduced by electrolytic oxidation of said aluminum cartridge case, saidlayer being integral with said case,fwhereby fusion of said case andwelding to said gun barrel in the firing of cartridges is prevented evenunder conditions of high temperatures;

2. A cartridge case comprising an aluminum containing case adapted foruse in a gun barrel and an aluminum oxide layer thereon, said layerbeing produced by electrolytic oxidation of said aluminum cartridge caseby means of a sulphuric acid bath, said layer being integral with saidcase, whereby fusion of said case and welding to said gun barrel in thering of cartridges is prevented under conditions of high temperatures.

3. A cartridge case comprising an aluminum containing case adapted foruse in a gun barrel and a layer thereon, said layer selected from thegroup of materials consisting of articially produced aluminum oxide,aluminum uoride and aluminum phosphate, said layer being integral withsaid case, whereby fustion of said case and Welding to said gun barrelin the firing of cartridges is prevented even under conditions of hightemperatures, the thickness of said oxide layer being considerablygreater than that formed by natural atmospheric oxidation of aluminum.

4. A cartridge case comprising a case consisting of an aluminum alloyadapted for use in'a gun barrel, and a layer thereon, selected fromY thegroup of materials consisting of artificially produced aluminum oxide,aluminum iiuoride and aluminum phosphate, said layer being integral withsaid case, whereby fusion of said case and welding to said gun "barrelin the firing of cartridges is prevented even under conditions of hightemperatures, the thickness of said oxide layer being considerablygreater than that formed by natural atmospheric oxidation of aluminum.

-5. A cartridge case comprising a case consisting essentially ofaluminum and adapted for use in a gun barrel and a firmly adherentsurface layer of an aluminum compound thereon, said surface layerexcluding a. welding of the cartridge case and the barrel wall offirearms, having a high melting point and being artificially producedfrom the material of the cartridge case by 'reaction with suitablesubstances to provide a layer taken from the class consisting of oxide,fluoride and phosphate.

6. A cartridge case comprising a case consisting essentially of aluminumand adapted for use in a gun barrel and a rmly adherent surface layer ofan aluminum compound thereon, said surface layer excluding a welding ofthe cartridge case and the barrel wall of firearms, having a highmelting point, comprising aluminum oxide and being artificially producedfrom the material of the cartridge case by reaction with suitablesubstances to provide a layer taken from the class consisting of oxide,iiuoride and phosphate.

7. A cartridge case adapted for use in a gun f barrel comprising analuminum containing case and a layer containing aluminum oxide thereon,said layer being artificially produced from the material of thecartridge case, being integral therewith and having a thickness of 0.1to 30 a, whereby fusion of said case and welding to said gun barrel inthe firing of cartridges is prevented even under conditions of hightemperatures, the thickness of said oxide layer being considerablygreater than that formed by natural atmospheric oxidation of aluminum.l

JCACHIM KORPIUN.

